People say that aptitude on Debian is so much better than apt-get, but I find it less usable. (See examples below.) Is there any configuration magic for aptitude to get rid of those useless status messages?

Usability does not really depend on the amount of output an application generates. Why do these status messages bother you? If it is because you have the output mailed to you on a daily basis, then I suggest you trim the output to the relevant lines using grep, probably with the -A option.